Electric lamp



Nov. 30, 1937. R. E. SMITH ELECTRIC LAMP Filed July 29, 1936 Frg. i.

by ywcfiwq His" Attorn e y.

2,130,879 ELECTRICLAMP metal-a a. Smith, am Cleveland, on... assign nor to General Electric Company, a corporation of New York Application July 29, 1936, Serial No. 93,236

' 4 Claims. (01. 176-16) I My invention relates to electric lamps and more particularly-to such lamps having a gas filling. Still more particularly, my invention relates to means for preventing the blackening of the bulbs or envelopes of such lamps.

In gas-filled electric lamps having a light source of refractory metal such as tungsten, vaporized particles of the metal are carried by the convection currents within the bulb and are deposited on the walls of the said bulb in the form of a dark coating which absorbs some of the light and thereby reduces the useful life of the lamp.

One of the objects of my invention is to provide a simple means for efiectively preventing the blackening of the bulbs of gas-filled lamps. According to my invention, bulb blackening is prevented by means of a screen, preferably a metal screen, located above the light source so as to be in the path of particles vaporized therefrom, the screen being so arranged as to provide a comparatively large surface extending along the path of the convection currents in the bulb for receiving the deposit of vaporized particles without materially affecting the path of the convection;

currents. Other features and advantages of my invention will appear from the following detailed description of a species thereof.

In the drawing, Fig. 1 is an elevation of a high intensity gas-filled incandescent lamp comprising my invention, and Fig. 2 is a section takenalong the line 2--2 of Fig. l.

Referring to the drawing, the lamp illustrated is of the so-called bipost type disclosed in Un'itcup or flare l3 secured thereto and sealed at its.

rim to the said glass cup ll. tend through openings in the glass cup ll into the bulb l0 and each has secured thereto an end of a rigid lead M which extends longitudinally into the bulb. A filament l5, preferably of tungsten, is mounted in the lower end of the bulb I0 and is of the monoplane type in which the coiled sections are located substantially in a single plane which preferably passes through the longitudinal axis of the bulb l0. Each of the ends of the said filament is secured to one of the leads l4 and the intermediate portions thereof are supported by the ends of upper and lower support wires l6 and ll. The opposite ends of said support wires l8 and I! are securedto bridges or blocks I8 and i9 respectively of insulating material extending between the leads IQ and secured thereto by pieces 5 of wire '26.

Blackening of the bulb l 0 is prevented and vaporized particles from the filament l5 are collected by a pair of wirescreens 2i each mounted on and preferably electrically connected to one to of the leads i i and extending to a position adjacent the opposite lead. The screens may be made of nickel and are preferably spot welded to the leads by means of narrow strips of metal 22 placed over the ends thereof. Additional sup- 15 p be in the path of particles vaporized therefrom.

The screens extend longitudinally of the bulb a substantial distance so as to provide a comparatively long surface which does notexcessiveiy impede the normal circulation of the gas in the bulb and yet readily collects the vaporized particles.

The action of the screen appears to beprincipally a mechanical one of intercepting the vaso porized particles carried along the screen by the convection currents. However, there also appears to be an advantage in electrically connecting .the screens tothe leads so that they are at the same potential as the leads, thereby creating 3 an electrical field between them, and also an .electric field between each screen and the lamp filament, which acts on the charged particles vaporized from the filament to cause them to be deposited on the screens. r

, 4 Since the vaporized particles are carried-upward by the convection currents, it is necessary 1 .that the lamp be used in such a position that The prongs l3 exthe screen is above the filament; The lamp base-up operation. In case it is desired to opershown in the drawing is, therefore, designed for ate the lamp base-down, it is necessary to inter change the positions of the filament I5 and screens 2| on the leads l4 so that the screens will be above the filament during operation of the 59 lamp. It is also possible to employ only one of the screens 2| instead'of two screens.

What I claim as new and'desire to secure by 1 Letters Patent of the United States is:

1. An electric lamp comprising .a bulb having 66 a gaseous atmosphere therein, a metallic light source in said bulb defining a substantially vertical plane and a fiat screen located substantially in the plane of said light source and above said light source when the lamp is in use so as to extend along the path of particles vaporized from said light source.

2. An electric lamp comprising a bulb having a gaseous atmosphere therein, a pair of leads extending longitudinally of said bulb, a metallic filament located between said leads substantially in the single longitudinal and vertical plane passing through said leads and electrically connected at each end to one of said leads, and a flat screen located between said leads and substantially in the said plane passing through said leads and above said filament when the lamp is in use so as to extend along the path of particles vaporized from said filament.

3. An electric lamp comprising a bulb having a gaseous atmosphere therein, a pair of leads extending longitudinally of said bulb, a metallic filament located between said leads substantially in the single longitudinal and vertical plane passing through said leads and electrically connected at each end to one of said leads, and a fiat metallic screen located between said leads and substantially in the said plane passing through said leads and above said filament when the lamp is in use so as to extend along the path of particles vaporized from said filament, said screen being electrically connected to one of said leads.

4. An electric lamp comprising a bulb having a gaseous filling therein, a pair of leads extending longitudinally of said bulb, a metallic filament of the monoplane type located between said leads in the plane passing through said leads and electrically connected at each end to one of said leads, and a pair of fiat metallic screens each mounted on and electrically connected to one of said leads and extending to a position adjacent the other lead, said screens being closely adjacent to the plane passing through said leads and being located above said filament when the lamp is in use so as to be in the path of particles vaporized from said filament.

- RICHARD E. SMITH. 

